Justin Tuck and the Giants need to play tougher defense against Antwaan Randle El and the ’Skins. Photo: Charles Wenzelberg/New York Post

Monday night is just about the football now — the Giants, the Redskins and a good, old-fashioned NFC East rivalry.

It wasn’t always that way at ESPN. When the cable sports giant took over the “Monday Night Football” broadcast in 2006, it went after the casual football fan by putting guests from the entertainment industry in the booth. It was not received well by most media and fans.

“I think some of it was unfair and blown out of proportion if you consider the guest was in for a drive or two during the three-hour telecast,” said “MNF” senior producer Jay Rothman. “We got a little beat up over that and sometimes justifiably so when we went a little too far outside the box.”

Some questioned if ESPN could carry on the legacy “MNF” created with the likes of Keith Jackson, Howard Cosell, Al Michaels, Frank Gifford and Dan Dierdorf. They hit the streets, talked to the fans and came to the realization that football fans wanted one thing — football.

“It was such a daunting task knowing the legacy,” said Mike Tirico, who has been the play-by-play man for MNF since ESPN took over.

“It’s our turn to carry this very well-respected mantle and to keep it as a very special place in TV. I know we try to do it every week and hopefully some people think we succeed at doing it.”

Out went the guests before 2008. In came Super Bowl-winning coach Jon Gruden for the departing funny-man/columnist Tony Kornheiser, who left because of the heavy travel schedule this season would have required. Now the telecast, which also includes holdover Ron Jaworski, has little to do with current events or comedy and everything to do with Xs and Os.

Gruden knew all about the history, saying he still gets chills every time he hears the theme song that played when Cosell was in the booth.

Giants fans have been getting the chills too this week — although a very different kind — when they think about how their team’s defense played against the Eagles in last week’s 45-38 loss.

“Losing your middle linebacker would have been catastrophic for the teams that I coached,” Gruden said about the Giants playing without Antonio Pierce. “You lose your signal-caller, the guy that makes all the adjustments and on top of that all the other injuries they have suffered in the secondary.

“And they just haven’t dominated in the front seven the way I thought they would. You combine that with the injuries and a new defensive coordinator and those things can cost you.”

Last week’s defeat put the Giants’ NFC East hopes on life support, but their playoff chances are still very much alive as they trail the Cowboys by one game for the final wild-card spot. But a loss in Washington — a definite possibility if Big Blue can’t reclaim their defensive prowess — and it’s time to start thinking about next season.

“This is a very dangerous game for the Giants,” Tirico said.

“Washington is playing very hard right now and this is the Redskins’ Super Bowl. If they can ruin the holidays for the Giants, that’s saving some of their season.”